Fear no more!
Run these to cut out a bunch of files that sonicomix's base doesn't use. This won't necessarily get everything, but should take care of a lot of it and make the remaining git status easier to browse.
# Remove albums
git rm src/content/dependencies/generateAlbum*
git rm src/content/dependencies/listAlbums*
git rm src/data/things/album.js
git rm -r src/data/composite/things/album/
# Remove art tags
git rm src/content/dependencies/generateArtTag*
git rm src/content/dependencies/listTags*
git rm src/data/things/art-tag.js
# Remove flashes
git rm src/content/dependencies/generateFlash*
git rm src/content/dependencies/generateArtistInfoPageFlashesChunkedList.js
git rm src/data/things/flash.js
# Remove groups
git rm src/content/dependencies/generateGroup*
git rm src/content/dependencies/listGroups*
git rm src/content/dependencies/generateArtistInfoPageArtworksChunkedList.js
git rm src/content/dependencies/generateArtistInfoPageTracksChunkedList.js
git rm src/content/dependencies/listArtistsByGroup.js
git rm src/data/things/group.js
# Remove tracks
git rm src/content/dependencies/generateTrack*
git rm src/content/dependencies/listTracks*
git rm src/data/things/track.js
git rm -r src/data/composite/things/track/
git rm src/content/dependencies/listArtistsByDuration.js
git rm src/content/dependencies/listArtistsByLatestContribution.js